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// $G $D/$F.go && $L $F.$A &&
// ((! sh -c ./$A.out) >/dev/null 2>&1 || echo BUG: should fail)
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import "unsafe"
var dummy [512<<20]byte // give us a big address space
func main() {
// the test only tests what we intend to test
// if dummy starts in the first 256 MB of memory.
// otherwise there might not be anything mapped
// at the address that might be accidentally
// dereferenced below.
if uintptr(unsafe.Pointer(&dummy)) > 256<<20 {
panic("dummy too far out")
}
// The problem here is that indexing into p[] with a large
// enough index jumps out of the unmapped section
// at the beginning of memory and into valid memory.
// Pointer offsets and array indices, if they are
// very large, need to dereference the base pointer
// to trigger a trap.
var p *[1<<30]byte = nil
println(p[256<<20]) // very likely to be inside dummy, but should crash
}
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